One way to accept or to "let it go", is to explore beliefs and values that you hold "TRUE", which may be preventing you from letting something go.
Examples of some common beliefs and values which impede the "letting go" process:
1 "We shouldn't be wasteful". This belief can lead to hoarding in the extreme.
2 "Things should be fair". This can result in much frustration because life is not always fair.
3 "The period of mourning/grief is proportional to the amount of care. Moving on after the death of a loved one shows a lack of care/respect." This greatly impacts the recovery after prolonged grief.
4 "If someone does something wrong, there should be consequences or punishments. There should be justice". This not only hinders forgiveness, but may also encourage spite.
Once aware, we can challenge these beliefs (CBT Cognitive Behaviour Therapy) or defuse from it, through validation and acknowledgement (ACT Acceptance Commitment Therapy). You cannot "TRY" to let go in my opinion, because letting go is, in essence, "NOT trying". So "letting go" is more about "unlocking" a belief through deeper understanding and validation rather then "doing". Ironically, many people say, "Yes, I am trying to let it go but I can't!"
Mindfulness practice will help one to be less judging and more "perceiving". It is this perceiving state of mind, that letting go, or acceptance becomes easier.
Once we realise that these are just beliefs and values that make us feel a certain way, we can then change them, or defuse from them, fostering a different relationship with them. It is no longer as fixed or as detrimental, as we initially thought.
"We shouldn't be wasteful" can be acknowledged that it is good in some situations but in the case of a child who has not finished his oily chips and you are full, it is not very helpful for you to eat those oily chips just because you feel that it is wasteful.
"Things should be fair"
This may be changed to ... "It would be nice if life is fair, but the reality is that it is not. Life is not fair and it is what it IS. I can only do my part to make it as fair as possible. Change what I can and let go of the things I cannot."
"The period of mourning/grief is proportional to the amount of care. Moving on after the death of a loved one shows a lack of care/respect."
This may be changed to... "My loved one would not want me to be in so much pain, and would like me to move forward and live the best life that I can. He/she would like me to honour him/her in this way".
"If someone does something wrong, there should be consequences or punishments. There should be justice"
This may be changed to ... "Letting go is important for me to reserve my energy for more important things in my life right now. I forgive them, for me, for my health and wellbeing, and for the important people in my life. Human beings are not perfect and they will have to learn from natural consequences. I don't have to be the judge or jury in their life".
We have all been conditioned to fix, rather than to let go, so these skill are not easy to foster. However, it is not impossible.
(It is also important to careful with over-challenging beliefs and values. It's important to validate first before the challenge otherwise it can come across invalidation).